550 



TRANS. ST. LOUIS ACAD. SCIENCE. 



sweeping plants and flowers with the net, I had never met with 

 any of the first larvae with which I had become familiar, as already 

 indicated ; while I had on several occasions, in digging ground 

 where there was no trace of bee nests, met with the curious 

 pseudo-pupa so characteristic of the Family. While analogy and 

 the law of unity of habit in species of the same family pointed, 

 therefore, to a parasitic life, I began to conclude, from the facts 

 just stated, that the parasitism was of another kind, having satis- 

 fied myself by various experiments that the triungulins did not 

 feed on roots. Few discoveries are stumbled upon. We find 

 as a rule that only which we anticipate or look for. Late last 

 Fall, in digging up the eggs of the Rocky Mountain Locust ( Ca- 

 loptenus spretus) at Manhattan, Kansas, the pseudo-pupae were 

 not unfrequently met with. The thought at once occurred to me 

 that locust eggs might be the proper food for these blister-beetle 

 larvae, and it was encouraged by the fact that the Meloids abound 

 most in those dry western regions where the Acrididae most pre- 

 vail, and by a pretty distinct recollection, which my notes support, 

 that the years when the vesicants were most injurious to potatoes 

 had been preceded by dry Falls, during which there had been 

 much locust injury and, necessarily, unusual locust increase. 

 The suspicion thus raised that these blister-beetles preyed in the 

 preparatory states upon locust eggs was confirmed last spring 

 by finding the larva of different ages within the egg-pods and 

 devouring the eggs of Caloptemis spretus, Mr. A. N. Godfrey 

 Fig. 38. had, also, no diffi- 



culty, under my di- 

 rections, in finding 

 them last May at 

 Manhattan; while 

 ^rx 4 W V they were sent to me 

 among other locust- 

 egg parasites by Mr. 

 Seth H. Kenney of 



Macrobasis uNicoLoR:-a, normal, gray form; J, black MorristOWn, Minn., 

 (>««r»«a) form; c, rf, male and female antennae of either. and from St Peters 



in the same State by Prof. Cyrus Thomas, who had no suspicion 

 of their nature. 



From such larvae preying on the eggs of spretus I have reared 



